Well, last Thursday night’s net (4/16/15) was yet another successful one with 11 check-ins plus net control (K6HWN). The net began with Garrett (AG6RQ) asking what the difference is between an antenna tuner and a matching network is. John (A6GLJ) was the first one to respond with the fact that what an antenna tuner really does is when it’s placed between the coax and transceiver it keeps the transceiver happy with the SWR level so it can deliver the maxim power to the load (antenna). If the transceiver detects too high of an SWR level it will restrict the amount of power output as to not damage the final amplifier stage. Cyril (AF6GW) offered up that maybe if the tuner was placed between the coax and the antenna it would be more of at true antenna tuner. Dave (K6HWN) agreed with Cyril except that it might be called an antenna impedance compensator, which is really what it does by changing the length of the antenna or the matching point. Cyril made a point that sure, the tuner might make the transmitter happy but the fact is that you still have the same feed line loss or bad antenna paring.

Don’t you wish you had tuned in? If so you can listen to the audio archive here.

John (AG6LJ) mentioned that this topic is one of the issues they’re currently dealing with using the fractional wave loop antennas. They’re really not designed to work on 12 meters, they can go with a solid state amplifier to about 200 watts, however with the impedance matcher/antenna tuner they can run full legal power. It basically tricks the system into working yet it’s not fully efficient but you can get the power out and at end of the day it works. Also discussed at this point was the concept of grid dipping in historical tube amps, and reversing the leads on an SWR meter to ascertain reflected power going back to the transceiver. (You can review the audio here).

Next Levi (K6LCM) had some follow-up regarding his attempt to use a Heil adapter to connect a headset with a boom mic and headphones to his rig. He was having trouble getting audio to the radio. (Solution can be heard here).

Now Cyril had some follow-up to a previous net’s question regarding suitable coating material for antennas, wires, enclosures, etc., that won’t affect the performance of the antenna. (Audio answer can be heard here).

Wish you’d been listening? Go here.

Lastly, I (K6FLD) posed a question regarding a strange hum or resonating I’ve been hearing in the walls or other source in my house using a new antenna. I purchased an end-fed antenna and on certain band frequencies I would hear a curious hum, seemingly coming from the walls of my home (at least that was my perception) when keying down the mic. On other band frequencies there was no discernible noise. Weird. So I purchased an MFJ-969 antenna tuner thinking that by properly matching the impedance at my rig it would eliminate the interference. Well, the other night I heard it again. A question was asked by Hayden (KK6OYV) if my station had an RF ground or not. My shack is on the second floor of my house with a deck and another 10 ft. drop impeding a short ground solution, so the answer was a resounding NO. Dave (K6HWN) mentioned the possible use of an artificial ground solution such as the MFJ-931. What the heck is that I asked??? Well, it turns out that if you connect the device between your rig and feed line or antenna tuner and feed line it reduces the electrical length of the ground connection wire to virtually zero by tuning out its reactance. Stay tuned to future nets to learn if I can solve my grounding issue!

Tune in to the SBARC Technical Mentoring and Elmering Net every Thursday night at 0800 on 146.79 and see what interesting questions will arise or ask some of your own! All club members and visitors are encouraged to check in to the Technical Mentoring and Elmering net each week and join in with questions and /or answers to and contribute the knowledge of new and seasoned amateur radio operators alike.

Last Thursday night’s net (4/9/15) was another successful one with 12 check-ins plus net control (K6HWN). The net began with John (A6GLJ) reminding everyone listening that Jerry’s (KK6FNP) single loop fractional wave antenna is for sale. Jerry is upgrading to a double loop fractional wave antenna and the single loop is making a trip to Arizona where the inventor of the technology will go over it and certify its well-being. The asking price is $2,000.00 USD and you can contact Jerry at (805) 896-4484 (no blocked numbers please) or jerryfarwest@aol.com. The antenna is described in greater detail in a swap net listing here at the Swap Net Listings.

Paul (KF6CIH) had listened to part of an ATV Special Modes net and had a question about how one can send computer data over the radio. Brian (K6BPM) was present on-air and being the net control for the Special Modes net happily went over some concepts with Paul and invited him to join the net if he’d like to learn more and participate. The net airs every Tuesday night at 8:00 PM to 9:30 PM on 146.79 linked to 224.08 and everyone is welcome to check-in.

Next Brian (K6BPM) asked a question that he and I (K6FLD) were curious about. I’d mentioned to Brian that when using my MFJ-969 antenna tuner that I thought I noticed enhanced signal reception when the antenna was tuned properly on a band. Brian and I (before I had ever used an antenna tuner) had thought that receiving wasn’t affected by tuning the antenna, only the SWR and transmit quality. Shackmaster Dave (k6HWN) explained that yes, indeed the receive will peak as well as the process is reciprocal in that what’s good for transmit is good for receive. Likewise, if you have loss on input you’ll also have loss on output. Signals will definitely peak on receive in fact you can tune it approximately by peaking it on receive noise and you’ll be close on transmit and SWR. Ken (KA6KEN) commented that it sounded like Brian had talked himself out of the idea that an electrical adjustment was being made during tuning when in fact you do, it’s just that you have passive components making a passive adjustment and you need not transmit for that to be beneficial.

Tune in to the SBARC Technical Mentoring and Elmering Net next Thursday at 0800 and see what interesting questions will arise or ask some of your own! All club members and visitors are encouraged to check in to the Technical Mentoring and Elmering net each week and join in with questions and /or answers to and contribute the knowledge of new and seasoned amateur radio operators alike.

Last Thurdsay night’s net (3/26/15)was successful with 14 check-ins plus net control (K6HWN). The net began with Yishen (KK6MJF) asking about apartment /dorm room antenna solutions. Apparently he’s not allowed to remove the screen from his window to extend a wire or any other type of antenna and was looking for another solution. Brian (K6BPM) offered probably the most practical solution, a magnetic mount car antenna attached a piece of “weldable” sheet metal (ground plane) about 12′ X 24″ placed on the window sill. This method works well for Brian at his office and might work well for Yishen too. Shackmaster Dave (K6HWN) offered his experience of using tops of cookie tins or mounting to the top of metal filing cabinets. Another solution Dave offered was the use of a gain antenna rather than the rubber ducky. All great suggestions.

Justin (K6LPZ) offered some of his experiences with handhelds and antennas. Over the years he’s found that bigger and more is better when it comes to VHF antennas. At one point he had a full length whip antenna reduced from a 239 connector down to BNC connected to his handheld transceiver and he could hear just about everything and his transmit was as good as could be expected with 2 watts.

Eric (K6HMD) asked if random wire antennas can be dangerous voltage wise and Dave answered that transmitting at high power it might be a problem but at lower power settings probably not more than any other antenna. There could be high voltage at the end where the antenna tuner transforms it down but again at lower power settings he probably wouldn’t worry too much about it. Eric offered some friendly advice to Yishen that of he went with a random wire setup not to get too close to it if everything’s indoors.

Yishen’s next question was regarding whether or not he should worry about grounding the antenna he’s planning to use and Dave asked a few questions including the radio Yishen would be using and the kind of antenna he’d be using. Depending on the type of antenna and what bands he’d be on it might improve the antennas performance if t were grounded.

Levi (K6LCM) asked about a 72 ft end-fed antenna at 40′ high he purchased from Brian, it works good on 80 meters but it’s noisy, in fact he’s been switching between two antennas for transmit and receive because of the noise. HWN commented that some radios can handle separate antennas for transmit and receive simultaneously and LCM will check his radio for that function. Brian mentioned that he had noticed a difference between the 72′ and the 88′ end-fed antennas in that his JT65 decodes were 3-4 db better with the longer antenna.

Finally Garrett (AG6RQ) asked if Q codes stood for anything or are they just arbitrary codes assigned to certain meanings. Dave mentioned that some sort of look like what they mean like QRP for low power or QRN for interference. Eric looked it up on wiki and we learned that they started out alphabetically like QRA, ARB, QRC, etc. then eventually morphed into what we use today. It was stated that Q codes really shouldn’t be used on VHF especially in an emergency because some folks wouldn’t understand them.

You can listen to the recorded version of the Technical Mentoring and Elmering Nets here.

Tune in to the SBARC Technical Mentoring and Elmering Net next Thursday at 0800 and see what interesting questions will arise or ask some of your own! All club members and visitors are encouraged to check in to the Technical Mentoring and Elmering net each week and join in with questions and /or answers to and contribute the knowledge of new and seasoned amateur radio operators alike.